The present invention is directed to an apparatus and method for the digital measurement of a difference in capacitance of two capacitors.
Such an apparatus or circuit arrangement can, for example, provide digital evaluation of differential capacitors. Differential capacitors are often utilized in sensor technology for measuring pressure, acceleration, humidity, slope, etc. Various devices have already been proposed for measuring differences in capacitance (see, for example, German reference DE 36 23 136, U.S. Pat. No. 4,392,378, German reference DE 41 03 433, European reference EP 0 503 272). In the known methods, the measured quantity (difference in capacitance) is represented either by the value of a voltage (or, respectively, of a current) or by the pulse-duty ratio of a PWM signal. An additional A/D conversion must occur in any case for a digital processing.